, it's just the way it is, and has been for the last 8 years when the financial requirements went through a change in 2017 when too many people were caught scamming the notarized wage statement option. Immigration after that required that all embassies attest that all wage declarations made on the form were accurate. Most embassies quit issuing them at that point, and also ended the combination of wages, and savings deposits.
if this is your second, or longer, year extending your extension of stay, you must have at least bt65,000 deposited from an overseas source every month with no exceptions. You can not be short one month, and be over the next month to make up for it. It is not a cumulative total over the whole 12 months. It is at least bt65,000 every month. If one month is short then the 12 month count restarts the following month. If that happens then the bt800,000 sum in the account for at least two months is again required, as the US embassy does not issue notarized wage statements that is the only other thing immigration accepts.
It is the easiest visa, and extension, to get yourself. Get a letter from your bank showing your current balance, over bt800,000, and a letter stating the account is yours, in your name only. These can be no more than seven days old. Make copies of your passport, and take all this to immigration and for bt2000 you'll get your type O retirement 90 day visa, and the list of what you need for your one year extension, which isn't much more. It is very easy to do yourself
From all the reports I've seen, the Thai embassy in the Philippines is the fastest, and easiest. Those applying in Vietnam have the longest wait now, up to two+ weeks.
after you get to Bangkok on the type O 90 day visa immediately open a Thai bank account in your name only, then go to immigration at Chaing Wattana, with your wife, and get the list of required documents, and pictures needed for your one year extension after the bt400,000+ has been in that bank account for at least two months, giving you time to get the rest of the documents required. Every time you go to immigration concerning your marriage visa extension always take your wife with you, or they won't talk to you, as they will tell her things in Thai that are not on the list, but required. That is how you do it. Don't try to overthink it. I'm still not sure you understand about the housebook she is listed in as a Thai citizen.